User:Serendipodous/indigo/page 17

Any mare on the Moon's far side Milkomeda Sgr A* Groombridge 34 Buffy and Biden Uranus Laneakea Supercluster Dimidium The outer scutum centaurus arm Proxima Centauri

Honourable mention: the sun and the moon, Fomalhout, Antares.

Innes was elected Fellow of the Royal Astronomical society at 17

He travelled to Australia and started a business selling wine.

His specialty was the identification of binary stars; a job requiring exceptional eyesight.

He took a relatively minor post at the Cape Observatory so that he could persue astronomy as a career

In 1903 he became the director of the Transvaal (later union) Observatory

refused to wear a tie

Wietze Nature November 2020
Team leader Jane Greaves, an astronomer at Cardiff University, UK, says she and her colleagues redid the work because they had learnt that the original ALMA data contained a spurious signal that could have affected the results. ALMA posted the corrected data on 16 November, and Greaves and her team ran a fresh analysis that night and posted it ahead of peer review on the preprint server arxiv.org.

The reanalysis found that phosphine concentrations in Venus’s atmosphere occasionally peak at five parts per billion. That means levels of the gas might wax and wane over time at different places on the planet, said Greaves — a situation similar to methane spikes appearing on Mars.

Where the phosphine comes from remains a mystery. Even at the one-part-per-billion level, there’s too much of it to be explained by volcanic eruptions at the planet’s surface or by lightning strikes in the atmosphere, several scientists said at the meeting. But phosphorus-based compounds might be produced by geological processes and then transform into other chemicals, such as phosphine, as they rise into the clouds, said Mogul.

The Indian Space Research Organisation is planning a Venus mission that would launch in 2025 and could potentially carry instruments capable of looking for phosphine.

Cool Worlds Jane Greaves
Parts per billion precision, prototypes telescopes

Result independently verified; reanalising the data, collecting further obersavations

ALMA: Phosphene signal not robust, subject to choices made during analysis- ALMA detected a calibration issue in thier data processing

JCMT: Signal not phosphene but sulphur dioxide

NASA Infrared telescope: no evidence for phosphene, upper limit of 5 parts per billion (originally 7)

Pioneer Venus multiprobe: sampled the gas of the atmosphere 50 km up, phosphorous detection

No clear consensus exists

greaves rechecked results (1-10 parts per billion) ALMA is now 5 sigma

spurious lines in the spectrum- now corrected

sulfur dioxide must be at 600 K; atmosphere at 300 K. Twice the largest value ever obsered required

Sky at Night
radio telescopes phosphine high atmosphere

On earth only made in factories or by bacteria

non-biological processes could only generate 1 ten thousandths of the amount seen

first planet we sent a probe to

Jane Greaves, James Clark Maxwell Telescope, Mauna Kea

anaerobic put out phosphine as a waste product- penguin crap, bacteria in guts

gas that would assess a possibilty for life. Some gases could indicate life but also could be abiotic

phosphine a biomarker that was difficult to produce through chemical means

The clouds above 50km, the temperatures and pressures are akin to the surface of the Earth- carl sagan

broken up after hours- constant production

absorbtion feature in radio- phosphine produces a unique signature at 1 mm

Venus is bright enough to cause reflections; 18 months of examining data

ALMA three rejections, and then a confirmation after new data

confirmation

polar regions of venus have no phosphine

dipping at the poles, circulating in the atmosphere

Every attempt to simulate natural phosphine generations consumed energy

Adding UV produced phosphine at one 10 thousandth the required amount

no subsurface, surface, clouds process produced phosphine beyond 10^-4

H2SO4 is incompatable with known biochemistry

a billion times as acidic

all new biochemistry

a protective shell? tough enough to withstand the environment? water in? H2SO4 out?

How do they eat?

succulent plant resistant to H2SO4

PBS
Venus light absorbers: dust churned up from the surface or microbes?

1967 Sagan and Harold Marwitz life in habitable atmosphere levels? gas bags?

atmospheric biosignatures- absorption of the planets own light as it emerges from deep within the atmosphere, visible at radio wavelengths where the glare doesn't kill the signal

more as a control; they didn't expect to find anything

formed in Jupiter and Saturn; abiotic formation (temperatures and pressures)

cool worlds
15 sigma 20 parts per billion

Sousa-Silva 2020
An ideal biosignature gas lacks abiotic false positives, has uniquely identifiable spectral features, and is unreactive enough to build up to detectable concentrations in exoplanet atmospheres. Phosphine fulfills the first two criteria: PH3 is only known to be associated with life and geochemical false positives for PH3 generation are highly unlikely (Bains et al. 2017; Bains et al. 2019a); PH3 possesses three strong features in the 2.7 – 3.6 microns, 4- 4.8 microns and 7.8 -11 microns regions that are distinguishable from common outgassed species that may be present in terrestrial exoplanet atmospheres, such as CO2, H2O, CO, CH4, NH3, and H2S. The greatest challenge to the detectability of phosphine at low surface fluxes is its reactivity to radicals, and its vulnerability to UV photolysis. In the most tractable observational scenario (planet orbiting an active M-dwarf), PH3 must be emitted at a rate of 1011 cm-2 s-1 to build to levels detectable by transmission or thermal emission spectroscopy (e.g., using JWST). The required PH3 production rates for detection are two orders of magnitude lower for planets orbiting a hypothetical “quiet” M-dwarf with extremely low levels of chromospheric activity; this latter scenario is likely unrealistic and corresponds to an extreme lower limit on the required PH3 flux.

greaves 2020
It was recently proposed that any phosphine (PH3) detected in a rocky planet’s atmosphere is a promising sign of life10. Trace PH3 in Earth’s atmosphere (parts per trillion abundance globally11) is uniquely associated with anthropogenic activity or microbial presence—life produces this highly reducing gas even in an overall oxidizing environment. PH3 is found elsewhere in the Solar System only in the reducing atmospheres of giant planets12,13, where it is produced in deep atmospheric layers at high temperatures and pressures, and dredged upwards by convection14,15. Solid surfaces of rocky planets present a barrier to their interiors, and PH3 would be rapidly destroyed in their highly oxidized crusts and atmospheres.

We know from the thermodynamic data summarized below (and presented in detail in ref. 35) that reaction with 12 stable species such as H2 cannot yield phosphine in adequate amounts from thermodynamic arguments.

We also checked for robustness by searching simultaneously for deuterated water (HDO) known to be present on Venus. The HDO 22,0–31,3 line at 1.126 mm wavelengWe are unable to find another chemical species (known in current databases23,24,25,26) besides PH3 that can explain the observed features. We conclude that the candidate detection of PH3 is robust, for four main reasons.th was detected (Extended Data Fig. 5: preliminary output from manual ‘QA2’ scripts), with a line profile well fitted by our radiative transfer model, and a Venus-normal water abundance (see ‘ALMA data reduction’ in Methods).#

PH3 is detected most strongly at mid-latitudes and is not detected at the poles (Table 1). The equatorial zone appears to absorb more weakly than mid-latitudes, but equatorial and mid-latitude values could agree if corrections are made for spatial filtering.

The presence of even a few parts per billion of PH3 is completely unexpected for an oxidized atmosphere (where oxygen-containing compounds greatly dominate over hydrogen-containing ones). We review all scenarios that could plausibly create PH3, given established knowledge of Venus.

) We find that PH3 formation is not favoured even considering ~75 relevant reactions under thousands of conditions encompassing any likely atmosphere, surface or subsurface properties (temperatures of 270–1,500 K, atmospheric and subsurface pressures of 0.25–10,000 bar, wide range of concentrations of reactants). The free energy of reactions falls short by anywhere from 10 to 400 kJ mol−1 (see ‘Potential pathways to PH3 production’ in Methods, Supplementary Information and Extended Data Fig. 7). In particular, we quantitatively rule out the hydrolysis of geological or meteoritic phosphide as the source of Venusian PH3. We also rule out the formation of phosphorous acid (H3PO3). While phosphorous acid can disproportionate to PH3 on heating, its formation under Venus temperatures and pressures would require quite unrealistic conditions, such as an atmosphere composed almost entirely of hydrogen (for details, see Supplementary Information).

Energetic events are also not an effective route to making PH3. Lightning may occur on Venus, but at sub-Earth activity levels33. We find that PH3 production by Venusian lightning would fall short of few-ppb abundance by factors of 107 or more. Similarly, there would need to be >200 times as much volcanic activity on Venus as on Earth to inject enough PH3 into the atmosphere (up to ~108 times, depending on assumptions about mantle rock chemistry). Orbiter topographical studies have suggested there are not many large, active, volcanic hotspots on Venus

Even if confirmed, we emphasize that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry. There are substantial conceptual problems for the idea of life in Venus’s clouds—the environment is extremely dehydrating as well as hyperacidic.

physorg
The team first used the James Clerk Maxwell Telescope (JCMT) in Hawaii to detect the phosphine, and were then awarded time to follow up their discovery with 45 telescopes of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Both facilities observed Venus at a wavelength of about 1 millimeter, much longer than the human eye can see—only telescopes at high altitude can detect this wavelength effectively.

Professor Greaves says, "This was an experiment made out of pure curiosity, really—taking advantage of JCMT's powerful technology, and thinking about future instruments. I thought we'd just be able to rule out extreme scenarios, like the clouds being stuffed full of organisms. When we got the first hints of phosphine in Venus' spectrum, it was a shock!"

Earth bacteria can absorb phosphate minerals, add hydrogen, and ultimately expel phosphine gas. It costs them energy to do this, so why they do it is not clear. The phosphine could be just a waste product, but other scientists have suggested purposes like warding off rival bacteria.

The molecule in question is PH₃ (phosphine). It is a highly reactive and flammable, extremely smelly toxic gas, found (among other places) in heaps of penguin dung and the bowels of badgers and fish.

Reading between the lines of the report, it seems that the team was not expecting to find phosphine. Indeed, they actively seemed to be looking for its absence. Venus was to supply the "baseline atmosphere" of a rocky planet, free from a phosphine biosignature. Scientists investigating rocky exoplanets would then be able to compare the atmospheres of these bodies with that of Venus, to identify any potential phosphine biosignature.

But the researchers, led by UK astronomer Jane Greaves, say their discovery "is not robust evidence for life" on Venus. Rather, it's evidence of "anomalous and unexplained chemistry," of which biological processes are just one possible origin.

Temperatures higher than 122℃ destroy most complex organic molecules. This would make it almost impossible for carbon-based life to form in very hot environment.

That said, this environment has its own limitations, such as clouds of sulfuric acid which would destroy any organic molecules not protected by a cell. For example, on Earth, molecules such as DNA are rapidly destroyed by acidic conditions, although some bacteria can survive in extremely acidic environments.

Becky
First detection in 2017, not confirmed until ALMA 20 ppb (others ten thousnad times less)

Ammonia but with phosphorus, next in the family

phosphine has a very unique signature- eight hours would be enough

summer 2017, data complicated, nothing there? looked again after getting some grant money from Cambridge

More telescope time, takes a long time

reducing environment gas giants hot with a lot of hydrogen

high clouds of venus not particularly hot, no hydrogen

active volcanoes? Grit? Gases?

thick hot atmosphere, chemical reactions?

Sunlight affecting the atmosphere?

Meteors, lightning?

mg per planet per year

probe? dirigible? months mission duration

data transfer could do in the probe lifetime

SciTechDaily
First and foremost, we need more information about the abundance of PH₃ in the Venus atmosphere, and we can learn something about this from Earth. Just as the discovery team did, existing telescopes capable of detecting phosphine around Venus can be used for follow-up observations, to both definitively confirm the initial finding and figure out if the amount of PH₃ in the atmosphere changes with time. In parallel, there is now a huge opportunity to carry out lab work to better understand the types of chemical reactions that might be possible on Venus — for which we have very limited information at present.

phys.org
A concept inspired by clockwork computers and World War I tanks could one day help us find out. The design is being explored at NASA's Jet Propulsion Laboratory in Pasadena, California.

The aerospace company Northrop Grumman has already independently developed a concept for a Venusian UAV, called VAMP (Venus Atmospheric Maneuverable Platform), which would have a giant 55-meter wing-span and be designed to operate in the atmosphere for at least a year.

In a paper published online today (March 30, 2018) in the journal Astrobiology, an international team of researchers led by planetary scientist Sanjay Limaye of the University of Wisconsin–Madison's Space Science and Engineering Center lays out a case for the atmosphere of Venus as a possible niche for extraterrestrial microbial life.

"Venus has had plenty of time to evolve life on its own," explains Limaye, noting that some models suggest Venus once had a habitable climate with liquid water on its surface for as long as 2 billion years. "That's much longer than is believed to have occurred on Mars."

On Earth, terrestrial microorganisms—mostly bacteria—are capable of being swept into the atmosphere, where they have been found alive at altitudes as high as 41 kilometers (25 miles) by scientists using specially equipped balloons, according to study co-author David J. Smith of NASA's Ames Research Center.

Those dark patches have been a mystery since they were first observed by ground-based telescopes nearly a century ago, says Limaye. They were studied in more detail by subsequent probes to the planet.

"Venus shows some episodic dark, sulfuric rich patches, with contrasts up to 30–40 percent in the ultraviolet, and muted in longer wavelengths. These patches persist for days, changing their shape and contrasts continuously and appear to be scale dependent," says Limaye.

The particles that make up the dark patches have almost the same dimensions as some bacteria on Earth, although the instruments that have sampled Venus' atmosphere to date are incapable of distinguishing between materials of an organic or inorganic nature.

The patches could be something akin to the algae blooms that occur routinely in the lakes and oceans of Earth, according to Limaye and Mogul—only these would need to be sustained in the Venusian atmosphere.

The Bio-inspired Ray for Extreme Environments and Zonal Explorations (BREEZE) project is one of 12 revolutionary concepts selected by NASA for its Innovative Advanced Concepts (NAIC) program, which funds early-stage technologies that could change what's possible in space. (Six other projects chosen in previous years received additional funding.)

Proposed by the university's Crashworthiness for Aerospace Structures and Hybrids (CRASH) Laboratory, researchers envision a morphing spacecraft with wings that flap like a stingray's pectoral fins. The design could make efficient use of high winds in the planet's upper atmosphere while providing scientists unparalleled control of the vehicle.

BREEZE would circumnavigate Venus every four to six days. Solar panels—charging every two to three days on the side of planet illuminated by the sun—would power instruments that take atmospheric samples, track weather patterns, monitor volcanic activity and gather other data.

"We know very little about the composition of the surface of Venus," she said. "We think that there are continents, like on Earth, which could have formed via past subduction. But we don't have the information to really say that." And that's not even with the benefit of Venus's dense atmosphere, where the experiment would likely return even stronger results.

So is there a chance that other types of life could survive unaided in Venus' atmosphere? The question of whether microbes could survive there has long been debated by planetary scientists as far back as Carl Sagan in 1967. Another paper in 2004 studied whether the sulfur in Venus' atmosphere could be used by microbes as a means for converting ultraviolet light to other wavelengths that could be used for photosynthesis. Still another study in 2018 proposed that the dark patches that appear in Venus' atmosphere could be something akin to the algae blooms that occur routinely in the lakes and oceans of Earth.

However, most previous studies concluded that any possible microbes in Venus' atmosphere could have only a short lifespan: They would fall through the clouds into the lower haze layer and end up incinerated in the heat and/or crushed in the higher atmospheric pressure that lies closer to the surface.

But now, a paper by astrobiologist Sara Seager and colleagues suggests that microbes could have a sustaining "life cycle," allowing them to survive for perhaps millions of years.

heir paper explores the possibility that microbes could live in the liquid environment inside sulfuric acid cloud droplets. As the droplet habitat in which the microbes reside grows, they would be forced by gravity to settle in the hotter, uninhabitable layer below the Venusian clouds. However, as the droplets begin to evaporate, the lower haze layer would become a "depot" for dormant life. Later, upward drafts would regularly lift the dormant microbes back into the clouds, where they would be rehydrated and become active again.

"Assuming that life must reside inside cloud droplets," the team wrote in their paper, published in the journal Astrobiology, "we resolve the subsequent conundrum of gravitationally settling droplets reaching hotter, uninhabitable regions by proposing a Venusian life cycle where a critical step is microbes drying out to become spores on reaching the relatively stagnant lower haze layer, which we call a leaky 'depot." The dried-out spores would reside there until some of them can be transported back up to the temperate, habitable cloud layers, where they would act as CCN to promote cloud formation, becoming enveloped in cloud droplets to continue the life cycle."

On Earth, terrestrial microorganisms—mostly bacteria—are capable of being swept into the atmosphere, where they have been found living at altitudes as high as 41 kilometers (25 miles).

There is also a growing catalog of microbes found to inhabit incredibly harsh environments on Earth, such as the hot springs of Yellowstone, deep ocean hydrothermal vents, the toxic sludge of polluted areas, and in acidic lakes worldwide.

P9
Scorpius–Centaurus Association

The handful of known planetary-mass companions at tens to hundreds of AU are already challenging planet formation theories, thus each addition to the set of directly imaged (DI) companions is valuable for understanding formation mechanisms. DI surveys are resource-intensive, as fewer than 20% of stars have giant planets at large orbital separations

The cluster has a mean age of 17 Myr, with an age-spread of ∼10 Myr. HD 106906 is a negligibly reddened, pre-main-sequence F5V-type star, with an isochronal age and mass of 13 ± 2 Myr and 1.5 M�,

we confirm common proper motion using Gemini NICI and Hubble Space Telescope archival data; present nearinfrared (NIR) spectroscopy of the companion to confirm its cool, young nature; estimate its mass using “hot start” evolutionary models;

MagAO/Clio2 is optimized for thermal IR wavelengths (3–5μm), where star-toplanet contrast is minimized

We do not consider “cold start” models, because formation by core accretion is impossible at hundreds of AU, and scattering into the current orbit is disfavored

hence the probability of a chance alignment within 7 is <1×10−5. We conclude that HD 106906 Ab is most likely a bound pair.

The presence of a massive disk (20-120 AU) around the primary argues against a scattering origin for the companion. We suggest it is more likely to have formed in situ in a binary-star-like process, though Mb/MA < 1% is unusually small.

HD 106906 is a 15 Myr old short-period (49 days) spectroscopic binary that hosts a wide-separation (737 au) planetary-mass ($\sim 11\,{M}_{\mathrm{Jup}}$) common proper motion companion, HD 106906 b. Additionally, a circumbinary debris disk is resolved at optical and near-infrared wavelengths that exhibits a significant asymmetry at wide separations that may be driven by gravitational perturbations from the planet.

In this study we present the first detection of orbital motion of HD 106906 b using Hubble Space Telescope images spanning a 14 yr period. We achieve high astrometric precision by cross-registering the locations of background stars with the Gaia astrometric catalog, providing the subpixel location of HD 106906 that is either saturated or obscured by coronagraphic optical elements. We measure a statistically significant 31.8 ± 7.0 mas eastward motion of the planet between the two most constraining measurements taken in 2004 and 2017.

With a periastron of ${510}_{-320}^{+480}$ au, HD 106906 b is likely detached from the planetary region within 100 au radius, showing that a Planet Nine–like architecture can be established very early in the evolution of a planetary system.